The present invention is a hydrosilation method comprising contacting a silicon hydride with an unsaturated reactant in the presence of a catalyst selected from a group consisting of amine borane complexes and phosphineborane complexes. The catalyst are especially useful for increasing selectivity for the hydrosilation of unsaturated reactants where the unsaturation is in the internal portion of the reactant's structure.
It is known in the art to produce organosilicon compounds by reacting a silicon hydride containing compound with an unsaturated organic compound in the presence of a catalyst. This reaction is typically referred to as hydrosilation or hydrosilylation. Typically the catalyst is platinum metal on a support, a platinum compound generally in a solvent, or a platinum complex.
In Speier et al., U.S. Pat. No. 2,823,218, a method for the production of organosilicon compounds by reacting an Si-H with a compound containing aliphatic carbon atoms linked by multiple bonds in the presence of chloroplatinic acid is taught. Lamoreaux, U.S. Pat. No. 3,220,972, teaches a similar process, however the catalyst is a eaction product of chloroplatinic acid.
One major limitation platinum has as a hydrosilation catalyst is that it is not particularly effective hydrosilating unsaturated organic compounds with an internal unsaturated bond and is known to produce multiple hydrosilation products that are difficult to separate. In addition to multiple hydrosilation products, when platinum catalyst is used to hydrosilate unsaturated organic compounds with an internal unsaturated bond, often the result is migration of the unsaturated bond such that silyl group bonds to the terminal carbon.
The present invention provides a method for hydrosilating unsaturated reactants for the preparation of organosilanes. The inventors have unexpectedly discovered that catalysts selected from the group consisting of amine borane complexes and phosphineborane complexes can be used in hydrosilation reactions. More particularly, these catalysts can selectively hydrosilate unsaturated organic compounds with internal unsaturated bond to increase the desired hydrosilation product yield.